Syria: Rebel groups clash with each other in Aleppo

Syrian rebel factions fought each other in besieged eastern Aleppo on Thursday, officials from two of the groups and a war monitor said, potentially undermining their efforts to fend off a major Russian-backed offensive.

Rebel groups have been plagued by disunity and infighting throughout the 5 1/2-year-old conflict, for ideological reasons, over tactical differences or in disputes over territory.